Fees and Expenses - AB Emerging Markets Multi-Asset Portfolio	Mar. 31, 2026 USD ($)
Prospectus [Line Items]
Expense Heading [Optional Text]	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Advisor Class shares, which are not reflected in the tables or the examples below. You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AB Mutual Funds. More information about these and other discounts is available from your financial intermediary and in Investing in the Fund—Sales Charge Reduction Programs for Class A Shares on page 29 of this Prospectus, in Appendix B—Financial Intermediary Waivers of this Prospectus and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 98 of the Fund’s Statement of Additional Information.
Expense Breakpoint Discounts [Text]	You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AB Mutual Funds.
Expense Breakpoint, Minimum Investment Required [Amount]	$ 100,000
Shareholder Fees Caption [Optional Text]	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Optional Text]	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Expenses Deferred Charges [Text Block]	Purchases of Class A shares in amounts of $1,000,000 or more, or by certain group retirement plans, may be subject to a 1%, 1‑year contingent deferred sales charge, or CDSC, which may be subject to waiver in certain circumstances.For Class C shares, the CDSC is 0% after the first year. Class C shares automatically convert to Class A shares after eight years.
Expense Example [Heading]	Examples
Expense Example Narrative [Text Block]	The Examples are intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Examples assume that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of the periods. The Examples also assume that your investment has a 5% return each year, that the Fund’s operating expenses stay the same and that any fee waiver and/or expense limitation is in effect for only the first year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Portfolio Turnover [Heading]	Portfolio Turnover
Portfolio Turnover [Text Block]	The Fund pays transaction costs, such as commissions, when it buys or sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in the Annual Fund Operating Expenses or in the Examples, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 135% of the average value of its portfolio.
Portfolio Turnover, Rate	135.00%

Fees and Expenses - AB Emerging Markets Multi-Asset Portfolio

Mar. 31, 2026

USD ($)

FEES AND EXPENSES OF THE FUND

This table describes the fees and expenses that you may pay if you buy, hold and sell shares of the Fund. You may be required to pay commissions and/or other forms of compensation to a broker for transactions in Advisor Class shares, which are not reflected in the tables or the examples below. You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AB Mutual Funds. More information about these and other discounts is available from your financial intermediary and in Investing in the Fund—Sales Charge Reduction Programs for Class A Shares on page 29 of this Prospectus, in Appendix B—Financial Intermediary Waivers of this Prospectus and in Purchase of Shares—Sales Charge Reduction Programs for Class A Shares on page 98 of the Fund’s Statement of Additional Information.

Expense Breakpoint Discounts [Text]

You may qualify for sales charge reductions if you and members of your family invest, or agree to invest in the future, at least $100,000 in AB Mutual Funds.

Expense Breakpoint, Minimum Investment Required [Amount]

$ 100,000

Shareholder Fees Caption [Optional Text]

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Optional Text]

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Expenses Deferred Charges [Text Block]

Purchases of Class A shares in amounts of $1,000,000 or more, or by certain group retirement plans, may be subject to a 1%, 1‑year contingent deferred sales charge, or CDSC, which may be subject to waiver in certain circumstances.For Class C shares, the CDSC is 0% after the first year. Class C shares automatically convert to Class A shares after eight years.

Expense Example [Heading]

Examples

Expense Example Narrative [Text Block]

The Examples are intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Examples assume that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the

end of the periods. The Examples also assume that your investment has a 5% return each year, that the Fund’s operating expenses stay the same and that any fee waiver and/or expense limitation is in effect for only the first year. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Portfolio Turnover [Heading]

Portfolio Turnover

Portfolio Turnover [Text Block]

The Fund pays transaction costs, such as commissions, when it buys or sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in the Annual Fund Operating Expenses or in the Examples, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 135% of the average value of its portfolio.

Portfolio Turnover, Rate

135.00%